package com.luojias.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

public class BaseDao {
    private static String driver;
    private static String url;
    public static String username;
    public static String password;
    //静态代码块，类加载的时候就初始化了
    static {
        Properties properties = new Properties();
        InputStream resourceAsStream = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        try {
            properties.load(resourceAsStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driver=properties.getProperty("driver");
        url=properties.getProperty("url");
        username=properties.getProperty("username");
        password=properties.getProperty("password");
    }
    //获取数据库连接
    public static Connection getConnection(){
        Connection connection=null;
        try {
            Class.forName(driver);
            DriverManager.getConnection(url,username,password);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return connection;
    }

    //编写查询公共类
    public static ResultSet execute(Connection connection,String sql,Object[] params,ResultSet resultSet, PreparedStatement preparedStatement) throws SQLException {
     //预编译的sql在后面执行就可以了
        preparedStatement = connection.prepareStatement(sql);
        for(int i=0;i<params.length;i++){
            preparedStatement.setObject(i+1,params[i]);
        }
        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }
    //编写增删改公共方法
    public static int execute(Connection connection,String sql,Object[] params, PreparedStatement preparedStatement) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for(int i=0;i<params.length;i++){
            preparedStatement.setObject(i+1,params[i]);
        }
        int updateRows=preparedStatement.executeUpdate();
        return updateRows;
    }
    public static boolean closeResource(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet){
        boolean flag=true;
        if(resultSet!=null){
            try {
                resultSet.close();
                //GC回收
                resultSet=null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag=false;
            }
        }
        if(preparedStatement!=null){
            try {
                preparedStatement.close();
                //GC回收
                preparedStatement=null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag=false;
            }
        }
        if(connection!=null){
            try {
                connection.close();
                //GC回收
                connection=null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag=false;
            }
        }
        return flag;
    }
}
